In the drawings accompanying this specification are illustrated various embodiments of the instant invention, wherein it is to be understood that similar reference characters in the different views designate corresponding parts throughout. Likewise, although a guitar of rather typical and conventional design is shown as being indicative of that type of musical instrument with which said invention and the alternate embodiments thereof are employed, it is further to be understood that the showing of such a guitar is intended to be illustrative only and not specifically limited per se thereto, but includes also various other musical instruments of the type having a fret board with a plurality of strings stretched therealong together in attachment upon a hollow body provided with a sound hole for effecting acoustic communication such as is structurally indicative, for example, of the banjo, ukulele, dulcimer, and the like.
More specifically, the instant invention comprises a musical instrument sound quality enhancement device in two embodiments respectively operable in two modes, the first embodiment being a simple and effective fully occlusive sound hole cover means whereby is enabled control of feedback interference in an electrical sound amplified stringed instrument system as well as a fixed tonal color variation change thereof when employed upon an instrument not utilizing the electrical sound amplification feature, and the second embodiment being a variably occlusive ported sound hole cover version which not only provides the foregoing electrically amplified feedback interference control feature but also enables one to effect selective tonal color variations of the stringed instrument by variable occlusion of the ported sound hole cover opening. Both of the invention embodiments and disclosed variations thereof employ in common opposingly positioned sets of spaced angularly outward and downward projecting pliable affixment fingers which enable mechanically cooperative insertably installed detachable attachment of the device within the stringed instrument circular shaped sound hole.
A sound hole cover feedback reducer for an acoustic electric guitar is known in the art, exemplary of which is that device as taught by Damiano in U.S. Pat. No. 4,394,830 dated July 26, 1983, and in particular that embodiment thereof as shown in FIG. 5 wherein a sound hole cover member is integrally provided with a plurality of resilient finger members being shaped with so-called "inclined detent cam surfaces" operable for effecting cover retention by deforming radially inward during sound hole insertable installation and returning to the undeformed retention attitude once insertable cover affixment has been accomplished and thereby collectively function to hold the cover in place.
A tone modifying sound hole cover device employment technique is taught by Ezaki in his U.S. Pat. No. 3,636,809 dated Jan. 25, 1972, wherein an instrument provided with dual opposingly positioned sound holes is made capable of generating a variety of tonal colors by the selective total occluding, or full opening thereof.
Lastly, a second hole cover mute is known in the art, as is taught for example by that construction shown in the FIG. 13 and 14 embodiments of U.S. Pat. No. 4,024,788 to Dunlap dated May 24, 1977, whereby the muting of a guitar is accomplished with a fully occlusive sound hole cover being provided with a downward projecting resilient member which extends into the sound hole covered thereby.
The instant invention, however, provides new and useful features in the art of musical instrument sound quality enhancement by a combination of elements not taught by the prior art, resulting in the present structures embodying construction features of novel merit as set forth hereinafter.